The present invention relates to an apparatus for automatically affixing a tape of composite material on the surface of an adhesion form having various contours to make a lamination of the tape.
In recent years, lightweight plate materials have been produced from a tape of composite material, i.e. a tape prepared by impregnating carbon fiber, aramid fiber or like reinforcing fiber with a thermosetting resin, by affixing the tape on the surface of an adhesion form (body) having specified contours to make a lamination, and thereafter subjecting the lamination to a curing treatment with application of heat and pressure. Unexamined Japanese patent application no. SHO 58-45057, for example, discloses a known method of automatically affixing such a tape of composite material. With this method, the tape is continuously paid off from a reel and pressed against the surface (curved surface) of the adhesion form with a press roller, the press roller is moved along a predetermined path to successively affix tape portions without leaving a clearance therebetween, and the tape affixing direction is changed from layer to layer, whereby a lamination is obtained.
A conventional tape feeding device is constructed as shown in FIG. 6. A single driven roller 36 is made to press against a drive roller 3 with a tape 10 being interposed therebetween. The tape 10 from a presser roller (not shown) is fed with the rollers 3, 36 and then wound by a take-up reel 25. Further, the drive roller 3 is attached with a rotary encoder (not shown) for detecting the feeding amount of the tape 10 based upon the rotation amount of the drive roller 3.
As shown in FIG. 8, it is required that an end edge of an affixed tape is in agreement with a border 10d of a predetermined adhesion region. An initial end of the tape 10 which is formed with cutters of a tape cutting device is put on a predetermined position on the presser roller, and then affixed on the adhesion form. If the initial end of the tape 10 is set off the predetermined position and then affixed to the adhesion form, the initial end comes to be out of the border 10d of the tape adhesion region corresponding to the offset distance. In view of the above facts, it is necessary to correctly control the feeding of tape.
In the arrangement of FIG. 6, a predetermined tension is always applied to the tape 10a on both take-in and take-out sides of the drive roller 3. However, not a little resistance arises to the tape feeding due to rotational resistance of each reel along the tape feeding path, and the moment of inertia of each reel when changing the feeding speed. Consequently, it is inevitable that a slip occurs between the tape 10a and the drive roller 3. It will be seen that the slip causes a difference between an actual feeding amount and a feeding amount obtained by the rotary encoder based upon the rotation amount of the drive roller 3. Additionally, it will be seen that a single driven roller is insufficient to prevent the tape from slipping. Further, even if the driven roller 36 is pressed against the drive roller 3 more firmly, a desirable feeding force is unobtainable, conversely, the movement of the tape is hindered and needless power is then consumed.
Moreover, a bulge effect is innegligible. As shown in FIGS. 7(a) and 7(b), when a presser member 64 is pressed against a portion between points A and B or a distance l.sub.0 on a surface 65 of resilient material such as rubber, the pressed portion is recessed to form a concavity 66 while the periphery of the pressed portion rises to form a convexity 67. Consequently, the distance between the points A and B comes to l.sub.1 which is larger than l.sub.0. Surfaces of the drive roller 3 and the driven roller 36 are made of resilient material such as rubber having a high friction coefficient to provide an increased feeding force. Consequently, as shown in FIG. 5, bulges (projection portions) 3a, 36a (34a) arises on both sides of a pressed contact portion of those rollers 3 and 36. The bulges on the right side are deformed to shapes 3b, 36b illustrated with solid lines due to a component 10f of the tension of the tape 10a. Consequently, the bulges on the right side have different shapes from those on the left side. In this case, even assuming that no slip occurs between the tape 10a and the drive roller and also that a rotary encoder for detecting the feeding amount of the tape 10a based upon rotation is attached to either the drive roller 3 or the driven roller 36, feeding amounts which are detected with respect to the same feeding differentiate depending on feeding directions. This is because of the following fact. The tape 10a is drawn between the rollers 3, 36 from the left bulges 3a, 36a when the feeding direction is "+" in FIG. 5 or a winding direction. The tape 10a is drawn between the rollers 3, 36 from the right bulges 3b, 36b when the feeding direction is "-" or a rewinding direction. However, the length of a drawn portion of the tape 10a or feeding amount is found out from the rotation amount of only one of the two rollers 3, 36. In view of the abovementioned facts, conventional apparatus involve errors in tape feeding.